MS is an autoimmune disease that attacks myelin, a protective sheath around the nervous system, and can lead to paralysis and sometimes blindness. There is no known cure.

When first diagnosed, most people are in the relapsing-remitting phase where they have intermittent symptoms, including difficulty walking or speaking and general pain, which are often partly reversible.

But some people don't respond to treatment, so the finding by researchers at Chicago's Northwestern University Feinberg School of Medicine points toward a potential treatment for this phase of MS. Their research will be reported in the March issue of the Lancet Neurology.

Previous studies had suggested it was possible to suppress the immune system and replenish it with new cells that develop from stem cells taken from the patient's bone marrow. In short, research indicated the patient's immune system could be "reset."